Acute refers to a medical condition, such as a muscular or joint injury that occurs suddenly resulting in a great change in well-being in a very short period of time, usually having a short duration.

With musculoskeletal injuries the term "acute" sometimes refers to the first phase of the injury healing period, beginning just after the injury occurs to differentiate this period from the post-management period.

Acute is used to describe the time-course of the onset of a pain or an illness and one that ends relatively quickly, either with recovery, or death.

An acute condition has symptoms that begin suddenly and can be traced back to a particular time, whereas many conditions have an insidious onset which comes about in such a manner that the person is not aware, initially, of having the condition and the condition does not have a well-defined starting point wherein symptoms are noticed, as is the case with many chronic conditions.

In medicine, the term acute often has the connotation of meaning also that the illness or pain is particularly severe or intense.